CONFIG_SPARC64 is not available for thedefaultarchitecture x86.
Result is shown for architecture sparc

CONFIG_SPARC64 (not configurable)

modulename: sysfs.ko

and/or

PeeCeeI.ko

and/or

visemul.ko

and/or

sbus.ko

and/or

reboot.ko

and/or

ultra.ko

and/or

starfire.ko

and/or

ebus.ko

and/or

pcr.ko

and/or

central.ko

and/or

jump_label.ko

and/or

prom_irqtrans.ko

and/or

iommu.ko

and/or

hvapi.ko

and/or

power.ko

and/or

nmi.ko

and/or

mdesc.ko

and/or

sstate.ko

configname: CONFIG_SPARC64

Linux/SPARC Kernel Configuration
└─>SPARC64
In linux kernel since version 2.6.12  
source code:
arch/sparc/mm/